Remote control mechanism



May 11, 1965 E. B. BURNETT 3,132,456

REMOTE CONTROL MECHANISM Filed May 9, 1963 5 Sheets-Sheet 1 v INVENTOR.ELMER B. BURNETT ATTORNEY y 1, 1965 E. B. BURNETT 3,182,456

REMOTE CONTROL MECHANI SM Filed May 9, 1965 5 Sheets-Sheet 2 F I3 I I I4y 1965 E. B. BURNETT 3,182,456

EEEEEEEEEEEEEEEEEEEEE SM Filed May 9, 1965 5 Sheets-Sheet 3 INVENTO ELMil 31;? B. BUR/VET y 1, 1965 E. B. BURNETT 3,182,456

REMOTE CONTROL MECHANISM Filed May 9, 1965 5 Sheets-Sheet 4 INVENTOR.ELMER B. BURNETT I I), I! 2 ATTORNEY May 11, 1965 E. B. BURNETT REMOTECONTROL MECHANISM 5 Sheets-Sheet 5 Filed May 9, 1963 V ra/fl!!!INVENTOR. ELMER B. BURNETT ATORNEY United States Patent C 3,182,456REMOTE CONTROL MECHANISM Elmer B. Burnett, Monroeton, Pa., assignor toIngersoll- Rand Company, New York, N .Y., a corporation of New JerseyFiled May 9, 1963, Ser. No. 279,133 3 Claims. (Cl. 60-545) Thisinvention relates to control mechanisms and more particularly to ahydraulic control device for remotely regulating the operation ofanother element or mechanism, such as a motor.

Presently in the control of overhead supported power hoists driven byair motors, pendent control devices are provided, which devices are airoperated and require three relatively large diameter hoses, one hoseleading from a source of pressurized air to the device, a second hoseextending between the device and the hoist for effecting the lifting ofa load, and a third hose extending between the device and the hoist foreffecting the lowering of a load. With hoses of relatively largediameter and relatively long length, large volumes of compressed airmust fill the hoses and be evacuated therefrom to effect appropriateresponse of the hoist motor. The necessity of moving large volumes ofair through the hoses to effect a desired response of the hoist motorresults in a time lag between actuation of the pendent control deviceand the appropriate response of the hoist motor. This disadvantage ofpresent pendent control devices for overhead supported hoists is morepronounced with larger size hoists since hoses of increased diameter arerequired.

Another disadvantage of the present air operated pendent controlassemblies is that they cannot be readily substituted for the mechanicalpull chain type of remote control means employed in some hoists.

It is, therefore, an object of the present invention to provide a remotecontrol assembly which effects rapid response of a slave mechanism.

It is another object of this invention to provide a pendent remotecontrol assembly which is capable of being relatively quickly and easilyinstalled on an overhead power hoist in place of a mechanical pull chaintype remote control device.

A further object of the present invention is to provide a hydrauliccontrol assembly of simplified construction which efiects quick andaccurate response of a mechanism whose operation is controlled by thehydraulic control assembly.

A still further object of this invention is to provide a hydrauliccontrol assembly which is a closed system requiring a relatively smallamount of hydraulic fluid under relatively low pressure.

In view of the foregoing, the present invention contemplates a novelhydraulic remote control system or assembly comprising, a control devicein combination with a slave mechanism such as a double-actingpiston-cylinder unit which is, in turn, constructed and arranged toactuate another'mechanism, such as an electric switch, fluid valve, orthe like.

The control device comprises a housing forming a liquid reservoirchamber in which is disposed means for constantly maintaining the liquidin the chamber under a slight pressure. The housing also provides a pairof identical and independently controlled piston valve assemblies. Eachpiston valve assembly has a piston chamber which communicates with theliquid reservoir chamber and with a slave mechanism through conduits ofrelatively small flow areas. A piston is disposed for reciprocation ineach piston chamber, which piston has a piston bypass passage thereinand a check valve to control flow of liquid through the by-pass passage.An axially movable plunger is slidably disposed in the housing adjacentice each of the pistons to engage and cause movement of the associatedpiston in the piston chamber. A by-pass valve control plate is mountedon the plunger for restricted slidable movement relative to the plungerand piston. The control plate is constructed and arranged to coact withthe check valve so that the check valve is maintained in an openposition, and when .the plunger moves the piston, the check valve isallowed to close.

A biasing means, such as a spring, is provided to urge the check valvein a closed position. Another biasing means which may be in the form ofa spring is disposed in each piston chamber to bias the associatedpiston in a direction toward one end of the piston chamber.

In operation of the control device, a plunger of one of the piston valveassemblies is slid by a manually actuated lever or by other suitablemeans. The movement of the plunger efiects slidable movement of thepiston. The initial movement of the plunger and piston is relative tothe control plate which permits the check valve to move to a closedposition under the urging of its biasing means. Further movement of thepiston effects displacement or" liquid which is immediately transmittedthrough the conduit to the slave mechanism to actuate the latter.Actuation of the slave mechanism causes actuation of another mechanism,such as an electric switch, fluid valve, or the like, to which the slavemechanism is connected. If the slave mechanism is in the form of adouble-acting pistoncylinder unit, the displaced liquid moves the pistonof the double-acting piston-cylinder unit commensurate with the amountof liquid displacement. This piston movement displaces a similar amountof liquid at the opposite end of the double-acting piston-cylinder unit,which liquid displacement is immediately transmitted through the conduitassociated with the other piston valve assembly and through the checkvalve and bypass passage in the piston to the liquid reservoir chamber.

The invention will be more fully understood from the following detaileddescription thereof when considered in connection with the accompanyingdrawing wherein one embodiment of the invention is illustrated by way ofexample and in which:

FIG. 1 is a View in elevation of the hydraulic remote control deviceaccording to this invention as applied to an air motor operated overheadsupported hoist.

FIG. 2 is a view in section taken along line 22 of FIG. 1 on an enlargedscale,

FIG. 3 is a view in perspective of the by-pass valve control plate,

FIG. 4 is a transverse sectional view taken along line 44 of FIG. 2,

FIG. 5 is a view in elevation of the remote control assembly shown inFIG. 1 on an enlarged scale and with parts in cross section forillustrative purposes, and

FIG. 6 is a view similar to FIG. 3 showing another operative position ofthe remote control assembly of this invention.

Now referring to the drawings and more specifically to FIG. 1, thereference numeral 10 generally designates the hydraulic remote controlassembly according to this invention as applied to controlling theoperation of an air motor driven hoist 11. While the hydraulic remotecontrol assembly 10 is shown and will be described as applied to anoverhead suspended power hoist 11, such application of the presentinvention is solely for illustrative purposes. The invention hasapplication to many different apparatuses wherein remote control of theoperation of a device or mechanism is desired as will be apparenthereinafter.

As shown in FIG. 1, the hydraulic remote control assembly 10 comprises amanually operated control device 12 connected by pendent hydraulic linesor conduits 13 and 14 to a slave mechanism 15 secured to the air motordriven hoist 11 which is of conventional construction 3,. well known tothose skilled in the art. struction of hoist 11 is of conventionaldesign well known to those skilled in the hoist art and the constructionof Since the conhoist 11 forms no part of the invention, hoist 11 willnot be described in detail.

Slave mechanism The slave mechanism 15 is illustrated as comprising twopiston-cylinder units 16, each of which is secured at a fiange. 17 to'amounting bracket 18 bolted to a valve chest 19 of hoist 11. Thepiston-cylinder units 16 are I mounted in juxtaposed relation to eachotheron opposite sides of a lever 20 which is connected to a reversingand throttle valve (not shown), the reversing and throttle".

unit 16 comprises a housing 22 of which flange 17 is inte-- gral.Housing 22 is provided with an end wall 23 and a bore 2 extending fromthe opposite end of the housing to a point short of end wall 23. Bore24is counterbored and threaded at 25 to receive a threaded end cap 26.Cap

26 is providedwith a bore 27 havingthe same diameter as bore 2 2- sothat, when the cap is turned into counterbore 25 of housing 22,,thesurfaces of bores 24 and 27 are coincident and form a piston chamber 28.A hole 31 of substantially smaller diameter than the diameter of bore 24is provided in end wall 23 of housing 22.

, A piston 32 having a head portion 33 and a stem portion34 is disposedfor reciprocation in piston chamber. 28 with the stern portion 34extending through hole 31 and projecting a substantial distance from endwall 23. Cap 26 is provided with a suitable threaded hole 35 whichcommunicates with piston chamber 28 and is adapted to receive a threadedhose connection 36 of the associated hydraulic line 13 or 14.

To seal the space between the piston head 33 and the walls of pistonchamber 23, a cup-shaped rolling diaphragm 37, known in the trade by thetrademark Bellotram, is secured to the piston head 33 by a cup-shapedretainer plate 38 and a screw 39 turned into a threaded axial hole inthe piston head to squeeze the rolling diaphragm 37 between the retainerplate 38 and piston head 33. The periphery ofdiaphragm 37 is providedwith a head 29. which is compressed in an annular groove formed inshoulder by cap 26. The bead 29 also serves as a seal to prevent leakageof fluid from piston chamber. 28 between housing 22 and cap 26. While aBellofrarn type of sealing means is shown and described, any other type.of seal means may be employed without departing from the scope andspirit of this invention.

A vent hole 4i) is provided in the end wall 23 of housing 22 to vent thepiston chamber on the non-working side of piston .32 and thereby providefree. reciprocation of piston 32.

As shown in FIGS. 1, 5, and 6, each of the pistoncylinder units 16 ismounted onthe valve chest 19 of hoist 11 so that the distal ends-of stemportions 34 of pis-.

tons 320i each piston-cylinder unit 16 abut opposite sides of lever 20.As can be readily seen, slidable movement a .of one of the pistons 32will cause the lever 2010 pivot and the other piston 32 to slidably movea distance corresponding to the distance of'movernent of the first men--tioned piston. Pivotal movement of lever 20 willefte'ct movementot thethrottle valve (not shown) of the hoist so that the speed and directionof operation of the hoist motor (not shown) are achieved.

Control device comprises a body portion or housing 41 and an elongatedhandle 42. A pair of plunger and piston assemblies 43 and 44 aredisposed within body portion 41, each of which assemblies controlsactuationof a piston-cylinder unit 16' of slave mechanism 15. Plungerand piston a'ssembly 44 controls actuation of piston-cylinder unit 16through line 14, while plunger and piston unit 43 controls actuation ofthe other piston-cylinder. unit 16 through line 13. Since each of theplunger and piston assemblies 43 and 44 is identical in construction,only assemblyp44 will be hereinafter described in detail.

Body portion 41 is provided with a bore 45 which has a counterboredportion 46-adapted to receive therein a cylinder sleeve 47; Bore 45 isprovided with another counterbored portion 48 which is=internallythreaded at 49 to receive anexternally threaded'plunger housing 50, thelatter being turned into threads '49 and into abutment against the endof cylinder sleeve 47 to; firmly hold the 3 cylinder sleeve in positionbetween the plunger housing and the shoulder 51 formed at the junctureof bore. 45 and counterbored portion 46. a The inner surfaces ofcylinder sleeve 47 and bore, 45 define a vpistin chamber in which isdisposed for reciprocative movement a piston 52.

As best illustrated in FIG. 2, piston 52 is provided with an axial .bore53 which has a counterbored portion 54 and a valve seat 55 formed at thejuncture of bore 53 and counterbored portion 54'. The outer end part ofcounterbored portion 54 is threaded to receive a screw 56 which has anaxial opening 57 extending therethrough. Screw 56 when turned intothethreaded part of counterbored portiorrS i engages a retainer cap 58to urge the latter toward the working face of piston 52 and therebysecure one end of a cup-shaped rollingdiaphragm 59 which is disposedbetween the working face of piston 52 and retainer cap 58. The peripheryof diaphragm 59' the tradeby the trademark .Bellofrarn and serves toseal the space between piston 52 and the inner surface of cylindersleeve 47. The rolling diaphragm 59' also functions to divide the pistonchamber formed by bore 45 and cylinder sleeve 47 into a working chamber66 and a nonworking chamber 61. The piston is biased in a directiontoward plunger housing .50 by a spring 62 which bears at one end againstthe bottom surface of bore 45 and at the opposite .end against retainercap 58. Bore 55, counterbored portion 54, and axialopening 57 constitutea piston by-pass'line. To control flow of fluid through the by-passline, a ball valve 63 is disposed in counterbored portion 54. Ball valve63 is biased in a direction toward seat 55 by a spring 64 which isdisposed between ball valve 63 and the inner end of screw 56.

The seating and unseating of ball valve 63 is achieved by a controlplate 65 which is carried by a plunger 66 and disposed between thelatter and piston 52. The construction and function of control plate 65willjhereinafter be more fully described.

Plunger 66 'is disposed 'forslidable movement in an axial recess 67'formed in plunger housing 56. An axial opening 68 of smaller diameterthau'recess 67v and com municating with the latter is provided inplunger'housing 56' to slidably receive therethrough a reduceddiameterstem portion 69 ofplunger66." A cup-shaped rolling diaphragm type seal'70, similarto rolling diaphragrns 37 and 59, is secured to the endofplunger 66 by a retainer screw 71 and a cup-shaped retainer plate 72.Retainer screw 71 is turned into a'threaded axial recess73' so as tourge retainer plate 72 toward plunger 66 and clamp rolling diaphragm 7 0between the retainer plate 72 and the end of plunger 66. The outerperipheral end portion of the diaphragm is clamped .between the end ofplungerhousing 51 and an 0 ring seal disposed in the annular spaceformed between counterbored portion 48 .1 and plunger housing 50. SealStifunctions to prevent fluid leakage from annular groove.81 through theinterstices between cylinder sleeve 47, counterbore 46, and threads 49to atmosphere.

Retainer plate 72 is provided, as best shown in FIGS. 2 and 4, with twospaced, axially extending guide walls 74. Guide walls 74 are arcuate inshape to receive and support therebetween control plate 65 so thatlimited relative axial movement of control plate 65 and plunger 66 ispermitted. As shown in FIG. 3, control plate 65 has a circular centralportion 75 and integral Wing portions or tabs 76 extending radially fromopposite sides of the central portion and partly lying in planes oflsetfrom the plane of the central portion 75. In addition, control plate 65has a pin 77 suitably secured at one end in an opening in the centralportion 75 and extending normal to the plane of the central portion. Asshown in FIG. 2, control plate 65 is positioned and dimensioned so thatone side of tabs 76 abuts against the inner end of plunger housing 50and the opposite sides of tabs 76 abut the end of piston 52, with pin 77extending coaxially within bore 53 to maintain ball valve 63 unseated.Also as shown in FIG. 2, guide walls 74 of retainer plate 72 abut theend of piston 52.

T o slidably move plunger 66 within recess 67 of the plunger housing 50,a trigger or lever '78 is pivotally mounted at one end to housing 41with the free end portion of the lever engaging the distal end of stemportion 69 of plunger 66. In operation, when lever 78 is depressed orpivoted inwardly toward housing 41, plunger 66 is moved in recess 67. Avent hole 79 is provided in plunger housing 50, which hole extends fromthe bottom of recess 67 to atmosphere.

Cylinder sleeve 47 is provided with an annular groove 81 in theperipheral surface thereof and a radial hole 82 extending from groove 81through the inner surface of cylinder sleeve 47 so as to communicatenon-working chamber 61 with groove 81. The purpose of groove 81 and hole82 will be hereinafter more fully explained.

To provide a reservoir of fluid under slight pressure for both pistonand plunger assemblies 43 and 44, a fluid reservoir chamber 83 isprovided. Chamber 83 is defined by a recess 84 formed in housing 41,which recess is counterbored and threaded at 85 to receive theexternally threaded end portion of handle 42. Handle 42 has an axiallyextending bore 86 which, when handle 42 is turned into the counterboredportion of recess 84, registers with recess 84 so that the respectivesurfaces of recess 84 and bore 86 lie in coplanar relationship to eachother. A piston 87 is disposed for axial movement within chamber 83 andis biased by a spring 88 toward the bottom of recess 84. Piston 87 isprovided with a cup-shaped rolling diaphragm 89, similar to rollingdiaphragm type seals 37, 59, and 70, to seal the space between thepiston and the inner surface of chamber 83. Rolling diaphragm 89 issecured to piston 87, in the same manner as rolling diaphragms 37, 59,and '70, by a cup-shaped retainer plate 90 and a screw 91 turned into athreaded opening 92 in piston 87. The outer periphery of the diaphragmis provided with a bead 42A which is clamped in a groove formed in theend surface of handle 42 between the latter and the shoulder at thejuncture of recess 84 and counterbore 85. As shown in FIG. 5, the bottomof bore 86 is closed by a threaded plug 93 which is provided with anaxial vent passage 94 to maintain the chamber below piston 87 atatmospheric pressure. As is best shown in FIG. 4, fluid reservoirchamber 83 is in communication with annular groove 81 of each of thepiston and plunger assemblies 43 and 44 through a pair of passageways95.

In the neutral position of piston and plunger assembly 44 of controldevice 12, as shown in FIGS. 2 and 5, working chamber 60 is incommunication with reservoir chamber 83 via passageway 95, annulargroove 81, radial opening 82, non-working chamber 61, and the pistonby-pass line consisting of bore 53, counterbored portion 54, and opening57. Communication of the piston bypass line with non-working chamber 61is effected through 5 the spaces between control plate 65 and guidewalls or arms '74 as can best be seen by viewing PEG. 4.

To convey fluid displaced in working chamber 68 to line 14 when piston52 is moved to the right as viewed in FIGS. 2 and 5, housing 41 isprovided with a passageway 96 which is counterbored and threaded at 97to receive a hose connection 98 of line 14.

Operation In operation of control device 12, depression of one of thelevers 78, as for example lever 78 associated with piston and plungerassembly 44, causes plunger 66 to move in axial recess 67 of plungerhousing in a direction to the right as viewed in FIG. 2. Since piston 52is in abutment against the ends of guide walls 74 of the retainer screw71, movement of plunger 66 forces piston 52 to move to the right asviewed in FIG. 2, thus displacing hydraulic fluid in Working chamber 60.Since control plate 65 is in abutment against plunger housing 50 and isurged thereagainst by spring 64 through ball valve 63, plunger 66 andpiston 52 move relative to the control plate until plunger 66 buttsagainst the circular portion 75 of the control plate. With the movementof piston 52 relative to control plate 65, ball valve 63 is brought intoseating relationship with seat to thereby close the piston by-pass lineand prevent flow of hydraulic fluid from working chamber 68 intoreservoir chamber 83. When the piston by-pass line is closed, furthermovement of plunger 66 and piston 52 against the force of spring 62displaces fluid in working chamber 60, which fluid displacement isimmediately transmitted by the fluid through passageway 96 and line 14to one of the piston-cylinder units 16 of the slave mechanism 15 tothereby cause a corresponding movement of piston 32 in a direction tothe left as viewed in FIGS. 5 and 6.

As best shown in FIG. 6 in which the extreme opposite operative positionof piston and plunger assembly 44 of control device 12 is illustrated,the fluid displaced in working chamber 68 forces fluid into pistonchamber 28 of the right-hand piston-cylinder unit 16 through line 14,thereby causing piston 32 to move in a direction to the left as viewedin FIG. 6. This movement of piston 32 actuates lever 28 and, in turn,effects movement of a throttle valve (not shown) of hoist 11.Simultaneous with movement of piston 32, piston 32 of the otherpiston-cylinder unit 16 is moved to displace fluid in its associatedworking chamber 28 (not shown). The fluid displaced in piston chamber 28of the other piston-cylinder unit 16 is transmitted through line 13 topiston and plunger assembly 43 of control device 12. Since thecomponents of piston and plunger assembly 43 are in the positions shownin FIG. 2, the fluid will flow from line 13, through passage 96, andinto working chamber 60. From working chamber 69 the fluid will flowthrough the piston by-pass line consisting of opening 57 in screw 56,counterbored portion 54, and bore 53. From the piston by-pass line thefluid will flow in the space between control plate and guide arm-s 74into non-working chamber 61. Thereafter, the fluid will flow intoreservoir chamber 83 via hole 82, an-

nular groove 81, :and passageway 95. Flow of fluid into reservoirchamber 83 exerts a pressure on piston 87, forcing the latter tocompress spring 88.

When the pressure exerted by the operator on lever 78 is released,spring 62 of plunger and piston assembly 44 returns piston 52 andplunger 66 to the position shown in FIG. 2. At the latter part of themovement of piston 52 and plunger 66 to the left as viewed in FIG. 2,the movement of control plate 65 is restrained by its abutment againstthe end of plunger housing 58 so that plunger 66 and piston 52 continueto move relative to control plate 65. This relative movement between thepiston, plunger, and control plate 65 brings pin 77 of the control plateinto engagement with ball valve 63, causing the latter to be unseatedfrom seat 55 and thereby opening the piston by-pass line to allow flowof fluid from chamber 28,

ansa rso through line 14, working chamber 66, the piston by-pass line,non-working chamber 61, hole 82, groove 81, and

passageway 95, into reservoir chamber 83. Simultaneous with movement ofthe piston SZand plunger 66 of piston and plunger assembly 44 to theleft-as viewed in FIGS. 2 and 6 and before the piston by-pass line isopened, fluid in reservoir chamber 33 is forced therefrom under theurging of spring 88 against piston 87 through passageway 95, groove 81,hole 82, non-working chamber 61, the piston by-pass line, workingchamber 60, passageway 96, 'line a 13, and thence into chamber 28 ofpiston-cylinder unit 16 on the left as viewed in FIG. 6. The entry offluid into the piston chamber 28 of this latter mentioned unit forcesthe associated piston 32 to the right as viewed'in FIG. 6 and therebyreturns lever 20 and the other piston-cylinder unit 16 to the neutralposition shown in FIG. 5.

Actuation of lever 78 of piston and plunger assembly 43 will result inthe same operation as herein above described except that such movementwill result in actuation of leverZtl in a direction opposite to thatshown in FIG. 6.

It is believed readily apparent that the remote control mechanism orsystem herein described provides a novel combination of a control deviceand slave mechanism, which system quickly and accurately responds to anoperators wishes and requires the movement of relatively smallquantities of fluid. The invention also provides in the control device asmall lost motion wherein initial depression of lever 78 will not effectoperation of slave mech-' anism 15 so that the operator has anopportunity to. realize his error should he begin to depress the wronglever. Furthermore, the invention provides a completely closed hydraulicsystem which operates under relatively low fluid pressures, thusproviding a system where sealing problems are negligible and thepossibility of leakage is minimal. In addition, since both ball valves63 in plunger and piston assemblies 43 and 44 are open when controldevice 12 is in the neutral or non-operating position, the remotecontrol assembly 10 is self-compensating to pressure changes caused bytemperature variationsor small fluid leakage. Also with both ball valves63 in the open position, lever 20 is unrestrained and may be movedwith-' out interference from slave mechanism 15.

In addition to the foregoing, the invention provides a hydraulic remotecontrol'mechanism which can be quickly and easily substituted for amechanical pull chain type of hoist control by merely substituting lever29 for the throttle control :arms at the ends of which are suspendedpull chains and mounting piston-cylinder units 16 to brackets 18 boltedto the valve chest 19 of the hoist.

Although but one embodiment of the invention has been illustrated anddescribed in detail, it is to be expressly understood that the inventionis not limited thereto. Various changes can be made in the arrangementof parts without departing from the spirit and scope of the invention asthe same will now be understood by those skilled in the art.

I claim:

1. A hydraulic control device for transmitting liquid to and receivingliquid from a slave mechanism to selectively effect operation of thelatter comprising,

(a) a housing having a liquid reservoir therein,

(b) said housing having at least one piston chamber therein,

(0) a piston disposed for axial movement in said piston chamber andbiased toward one end of the piston chamber to define between the pistonand the.

opposite end of the piston chamber a working 7 chamber,

(d) a by-pass passage extending axially through said pistoncommunicating at one end with the working chamber and at the oppositeend with the liquid reservoir to provide flow of liquid past the piston,

(e) actuating means for axially moving said piston in said pistonchamber to displace liquid in the working chamber,

(f) a check valve in said by-pass passage for controlling flow of liquidthrough the latter, and

(g) means cooperatively associated with said actuating means and saidcheckvalve to maintain said check valve open when said piston is at saidone end of the piston chamberand to allow said check valve to close whenthe piston is moved toward said opposite end of the piston chamber,

(12) said last mentioned means comprising a plate carried by saidactuating means for restricted slidable imovementrelative thereto,

(1') said plate having a projection disposed to extend into said by-passpassage to engage the check valve and maintain said check valve in anopen position when said piston is at said one end of said piston chamberand disengage from'said check valve to allow the latter to close whenthe piston is moved toward said opposite .end of said piston chamber.

2. A hydraulic control device for transmitting liquid to andreceivingliquid from a slave mechanism to selectively to effect operation of thelatter comprising,

(a) a housing having a liquid reservoir therein,

(b) said housing having at least one piston chamber therein, v

(c) a piston disposed for axial movement insaid piston chamber,

(d) biasing means for urging said piston in a direction toward one endof the piston chamber to define between the piston and the opposite endof the piston chamber a working chamber,

(e) a coaxial thy-pass passageway formed in said piston communicating atone end with the. working chamber and at the opposite end with saidliquid reservoir to providefiow of liquid past the piston,

(f) a plunger disposed in said housing adjacent said piston for axialmovement to engage and axially move said piston toward said opposite endof the piston chamber,

(g) trigger means disposed to engage said plunger and to axially movethe latter,

(h) a valve seat formed in'said by-pass' passageway,

(i) a ball valve'disposed in said by-pass passageway and biased towardsaid valve seat in said by-pass passageway, and I .(j) a ball valvecontrol plate carried by said plunger adjacent said piston,

(k) said ball valve control plate, having a projection disposed toextendpinto said .by-pass passageway and. into engagement-with said ballvalve to maintain said ball off said Valve seat when the piston is atthe said one end ofthe piston chamber,

(1) said ball valve control plate carried by said plunger and capable ofrestricted axial movement relative to the plunger so that, upon movementof the plunger 7 and the piston, the control plate and its projectionmove relative to the plunger and piston to allow the ball valve to restagainst the valve seat and thereby prevent flow of liquid through theby-pass passageway.

3.'A hydraulic control devicecomprising in combination with adouble-acting piston-cylinder. unit having a piston chamber means and apiston means reciprocable in said piston chamber means and wherein saidpiston means is connected to another element to operate the latter, saidhydraulic control device comprising,

(a) a housing having a liquid reservoir therein,

(b) said housing being: provided with a first piston valve assembly anda second piston valve assembly,

(0) each of said first and second piston valve assembliescomprises apiston chamber,

(d) a piston disposed for reciprocation in said piston chamber andbiased toward one end of said,

piston chamber to define between the piston and the opposite end of thepiston chamber a working chamber,

(e) a by-pass passage in said piston communicating at one end with theWorking chamber and at the opposite end with the liquid reservoir toprovide for flow of liquid past said piston,

(f) a valve disposed in said by-pass passage for controlling flow ofliquid past said piston,

(g) plunger means disposed for slidable movement in said housingadjacent said piston for moving said piston in said piston chamber, I

(h) manually controlled means for slidably moving said plunger,-

(i) valve actuating means cooperatively associated with said plunger andsaid valve to maintain said valve means open when said piston is at saidone end of said piston chamber and to permit said valve to close whensaid piston is moved toward said opposite end of the piston chamber,

(j) said valve actuating means comprising a plate carried by saidplunger and having a projection disposed to extend in said by-passpassage to engage and maintain said Valve open when the piston is atsaid one end of the piston chamber,

(k) a first passage means in communication at one end with the workingchamber of the first piston valve assembly and at the opposite end withone end of said piston chamber means of the piston-cylinder unit totransmit liquid displaced by the piston of said first piston valveassembly to the said one end of the piston chamber means to actuate thepiston means of the doubleacting cylinder-piston unit, and

(l) a second passage means in communication at one end with the workingchamber of the second piston valve assembly and at the opposite end withthe other end of the piston chamber means of the piston-cylinder unit toreceive liquid displaced by said piston means of the piston-cylinderunit and transmit the same through the by-pass passage in the piston ofthe second piston valve assembly to the liquid reservoir.

References Cited by the Examiner UNITED STATES PATENTS 1,693,068 11/28Cowles 60-54.6 X 2,189,013 2/40 Loweke 6054.5 2,246,140 6/41 Main 6054.62,847,827 8/58 Johnson 6054.6 2,871,662 2/59 Nagel et al. 6054.52,946,196 7/60 Myetrs 6054.6 X 2,968,154- 1/61 Richey 6054.5 3,120,244-2/64 Hahn 60-545 X 3,125,200 3/64 Kaman 60--54.6 X

FOREIGN PATENTS 626,073 7/ 49 Great Britain. 765,301 1/ 57 GreatBritain.

JULIUS E. WEST, Primary Examiner.

'30 ROBERT R. BUNEVICH, Examiner.

2. A HYDRAULIC CONTROL DEVICE FOR TRANSMITTING LIQUID TO AND RECEIVINGLIQUID FROM A SLAVE MECHANISM TO SELECTIVELY TO EFFECT OPERATION OF THELATTER COMPRISING, (A) SAID HOUSING HAVING A LIQUID RESERVOIR THEREIN,(B) SAID HOUSING HAVING AT LEAST ONE PISTON CHAMBER THEREIN, (C) APISTON DISPOSED FOR AXIAL MOVEMENT IN SAID PISTON CHAMBER, (D) BIASINGMEANS FOR URGING SAID PISTON IN A DIRECTION TOWARD ONE END OF THE PISTONCHAMBER TO DEFINE BETWEEN THE PISTON AND THE OPPOSITE END OF THE PISTONCHAMBER A WORKING CHAMBER, (E) A COAXIAL BY-PASS PASSAGEWAY FORMED INSAID PISTON COMMUNICATING AT ONE END WITH THE WORKING CHAMBER AND AT THEOPPOSITE END WITH SAID LIQUID RESERVOIR TO PROVIDE FLOW OF LIQUID PASTTHE PISTON, (F) A PLUNGER DISPOSED IN SAID HOUSING ADJACENT SAID PISTONFOR AXIAL MOVEMENT TO ENGAGE AND AXIALLY MOVE SAID PISTON TOWARD SAIDOPPOSITE END OF THE PISTON CHAMBER, (G) TRIGGER MEANS DISPOSED TO ENGAGESAID PLUNGER AND TO AXIALLY MOVE THE LATTER, (H) A VALVE SEAT FORMED INSAID BY-PASS PASSAGEWAY, (I) A BALL VALVE DISPOSED IN SAID BY-PASSPASSAGEWAY AND BIASED TOWARD SAID VALVE SEAT IN SAID BY-PASS PASSAGEWAY,AND (J) A BALL VALVE CONTROL PLATE CARRIED BY SAID PLUNGER ADJACENT SAIDPISTON, (K) SAID BALL VALVE CONTROL PLATE HAVING A PROJECTION DISPOSEDTO EXTEND INTO SAID BY-PASS PASSAGEWAY AND INTO ENGAGEMENT WITH SAIDBALL VALVE TO MAINTAIN SAID BALL OFF SAID VALVE SEAT WHEN THE PISTON ISAT THE SAID ONE END OF THE PISTON CHAMBER, (L) SAID BALL VALVE CONTROLPLATE CARRIED BY SAID PLUNGER AND CAPABLE OF RESTRICTED AXIAL MOVEMENTRELATIVE TO THE PLUNGER SO THAT, UPON MOVEMENT OF THE PLUNGER AND THEPISTON, THE CONTROL PLATE AND ITS PROJECTION MOVE RELATIVE TO THEPLUNGER AND PISTON TO ALLOW THE BALL VALVE TO REST AGAINST THE VALVESEAT AND THEREBY PREVENT FLOW OF LIQUID THROUGH THE BY-PASS PASSAGEWAY.